Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sony DT 50mm F1.8 SAM is the longer of the two lenses at 45mm. The Lensbaby Sol 45 DSLR with a length of 39mm is 6mm shorter. On the other hand, the Lensbaby Sol 45 DSLR has a larger diameter of 73mm compared to Sony DT 50mm F1.8 SAM's 70mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Lensbaby Sol 45 DSLR weighs 144g, which means it is 26g (18%) lighter than the Sony DT 50mm F1.8 SAM which has a weight of 170g.
Lens Mounts
Both Lensbaby Sol 45 DSLR and Sony DT 50mm F1.8 SAM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Lensbaby Sol 45 DSLR is also available in Canon EF , Fujifilm X, Nikon F (FX) and Pentax KAF mounts.
Focal Range
Lensbaby Sol 45 DSLR is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 67.5mm.
Sony DT 50mm F1.8 SAM is a prime lens with fixed focal lenght of 50mm which has a 35mm equivalent focal range of 67.5mm when used on a APS-C / DX format camera.